This application is based on Japanese Patent Application No. 09-133160 filed on May 23, 1997, the contents of which is incorporated herein by reference.
1. Field of the Invention
This invention relates to a method of and an apparatus for producing images in a virtual space, and to an image pickup system suitable for use therein.
2. Description of the Prior Art
In order to form a three-dimensional image by a computer, it has been conventional practice in the past to resort to geometry based rendering (GBR) or image based rendering (IBR).
The GBR is a comparatively long-established method, whereby the sharply defined shape and position of an object are obtained such that one object is allowed to collide with or hide itself behind another under conditions closely approximating actual conditions. On the other hand, GBR is not suitable for use in illustrating an object in complicated shape, because the three-dimensional shape obtained from GBR is a combination of fundamental figures. It is difficult, therefore, to form an image true to nature to the extent of looking as if it were a photograph.
The IBR is a method of providing, on the basis of a plurality of two-dimensional images, what an object looks like when it is viewed from various visual points. In recent years, notable progress has been made in this field. Although the shape and position of the object are not sharply defined, it is comparatively easy to form an image true to nature to the extent of looking as if it were a photograph.
Heretofore, video conference systems have been utilized to enable persons present in different localities to hold a conference. A video conference system comprises video cameras and display apparatuses provided in rooms located in different localities. These video cameras and display apparatuses are connected to each other by means of telecommunication lines. The personal appearance of attendance is photographed by means of the video cameras provided in the respective rooms. Image pickup signals are directed toward the other end of each telecommunication line and displayed on the screen of the display apparatus provided in the room involved.
The prior art video conference system has the disadvantage that it does not allow a speaker to behave as he or she pleases. More specifically stated, the speaker has to face the display apparatus which is fixedly held in position and has only a limited screen area; the visual axes of the speaker""s eyes are bound to the video camera disposed in the immediate vicinity of the display apparatus; and the speaker is so conscious of the video camera that he cannot feel as if he were in the same room with the listeners present at the other end of the telecommunication line.
Two video cameras disposed in spaced relation with each other in each room and a display apparatus provided with a lenticular screen in each room may be regarded as suitable for allowing the speaker to have a stereoscopic vision of the listeners and allowing the listeners to have a stereoscopic vision of the speaker. Even in this case, however, it is very difficult to allow them to have a stereoscopic vision irrespective of their visual points.
The present invention is concerned with eliminating these various difficulties. As such, the primary object of the invention is to provide a method of and an apparatus for producing images in a virtual space and an image pickup system suitable for use therein so as to enable persons present in different localities to feel as if they met together in a room.
In accordance with the invention, light beams directed toward virtual visual points are detected from among light beams emitted from or reflected on the surface of an object. The detection is effected by an image pickup device in a plurality of positions lying on a virtual closed surface with which the object is enclosed. The detected light beams are converted into image pickup signals, which are delivered to a display device adapted to display an image toward a visual point of an observer standing or sitting in a place different from a place where any of the virtual visual points is disposed. The image is displayed in such a manner as if light beams were emitted toward the visual point of the observer from various points on the surface of a virtual object disposed in a virtual position corresponding to the relative positions of the real object and any of the virtual visual points.
An image pickup device such as shown in FIG. 7 may be used in the apparatus of this invention. This image pickup device comprises an upright CCD line sensor CL and a cylindrical housing or jacket disposed circumferentially around the CCD line sensor CL and provided with a slit aperture STm extending longitudinally along a generatrix. The image pickup device rotates on its own axis while being advanced along a circular path of travel.
This image pickup device records light beams received from directions determined by positions in which the image pickup device is located along the circular path of travel. An image formed by light beams received in a specific position and from a specific direction is hereinafter referred to as a xe2x80x9clinear imagexe2x80x9d.
Instead of the CCD line sensor CL, it is also possible to use a CCD area sensor CE incorporated in a camera CM as shown in FIG. 16. Vertical scan is associated with auxiliary scanning effected in a horizontal direction. Vertical scan makes it possible to obtain a large number of scanning lines. An image formed by one of them specified by a position and a direction is also hereinafter referred to as a xe2x80x9clinear imagexe2x80x9d.
In order to afford to an observer an overall view of the object field, necessary linear images specified by positions and directions are selected from among all the linear images and delivered to the display device for image reconstruction.
A display device such as shown in FIG. 3 may be used in the apparatus of this invention. This display device comprises full-color LED matrixes EX adapted to be advanced along a circular path of travel. On the basis of the aforesaid linear images, images for the left and right eyes respectively of an observer are afforded to him or her. If the display device has an inner cylindrical surface covered all over with the LED matrixes EX, it need not be of a revolving type.